This invention relates to an improved crankshaft apparatus to form a mechanical couple between a drive shaft and a piston arranged to reciprocate within a cylinder for an improved relationship of moving parts as compared with a conventional lobe-type crankshaft. The crankshaft apparatus of the invention is particularly advantageous for an internal combustion engine or compressor wherein a fluid medium is compressed incident to the operation thereof by employing a constant diameter cam having a cam surface in contact with two equal diameter follower rollers at generally diametrically-opposite points. More specifically, the present invention is directed to the development of a particular cam surface including, if desired, harmonics of the developed surface and/or additional motion control members for producing a greater torque in the drive output shaft of an internal combustion engine.
The power delivered from an internal combustion engine is directly proportional to the torque applied to the output shaft and the rotary speed. Gasoline, gas or diesel engines designed for a two-cycle or four-cycle operation use a crankshaft and a connecting rod in a mechanical system to change the reciprocating motion of the piston to rotary motion of the output shaft. The throw of the crank requires the connecting rod to assume various angles to the direction of movement of the piston whereby the transmission of torque per unit of force between the crankshaft and the piston is not always efficient. At the time of maximum torque per unit of force by expansion of gases on the piston, i.e., about 80.degree. of rotation after top dead center, the lobe of the crank moves to a large non-aligned relation with movement of the piston. Torque from the crank is resolved into a force on the piston in another part of the operating cycle of an internal combustion engine; and in a similar way, in a piston-type air compressor. In this instance, an undesirably large torque per unit of force is required because of the angular relation between the lobe of the crank and the piston. This invention is addressed to an improved crankshaft apparatus having preferred forms to produce substantially greater torque during the power stroke in an internal combustion engine as compared with a conventional crankshaft apparatus. The invention further provides an improved crankshaft apparatus which is designed to take greater advantage of the pressure curve developed in an internal combustion engine during the power stroke. The improved crankshaft apparatus reduces the required torque per unit of force during the compression stroke by an engine as well as by a piston-type compressor.